if prev:
html_file.write("#attr $Prev = \"%s.html\"\n" % prev)
if next:
html_file.write("#attr $Next = \"%s.html\"\n" % next)
if prev:
html_file.write("#attr $Prev = \"%s.html\"\n" % prev)
if next:
html_file.write("#attr $Next = \"%s.html\"\n" % next)
html_file.write('#attr $alternates = (("Plain text version", "text/plain", "%s"),)' % txt_name)
html_file.write("\n")
html_file.write("#def body_html\n")
html_file.write('#attr $alternates = (("Plain text version", "text/plain", "%s"),)' % txt_name)
html_file.write("\n")
html_file.write("#def body_html\n")